1. The lamp is in an environment with high humidity and high temperature, and the air humidity in the lamp is relatively high. When the ambient temperature decreases, the water vapor in the lamp cannot fully flow and diffuse into the environment, and still maintain a high level. Humidity, fogging occurs when the temperature in some areas of the lamp is lower than the local critical temperature of water vapor.
2. The temperature of the area where the light energy is irradiated and the air is circulated is very high, but the area where the light cannot be illuminated in the headlight, and the temperature in the area with poor air flow will be very low, which will cause uneven temperature distribution in the lamp, forming a larger area. Temperature difference; especially in the lamp cavity, due to its uneven surface, it provides a very favorable place for water vapor condensation.